Electronic volume control system

ABSTRACT

An electronic volume control system has an UP key (1) for increasing the level of volume, a DOWN key (2) for decreasing the level of volume and a control (3) for controlling to increase or decrease the level of volume at the primary rate of volume change, based on the operation of each of the keys (1 and 2). The control (3) can set a fine adjustment mode in which the level of volume can be increased or decreased at a secondary rate of volume change which is smaller than the primary rate of volume change. The control (3) sets the fine adjustment mode when the time interval from a time point when one of the keys (1 or 2) is turned off to another time point when one of the keys (1 or 2) is subsequently turned on is within a preset time period. In order to enable the setting of the fine adjustment mode, a preset time period is set in UP-key or DOWN-key counter (10 or 11), if required. This preset time period is counted down for each unit time. If any key is turned on before the output of the counter becomes &#34;0&#34;, the fine adjustment mode is selected.

TECHNICAL FIELD

The present invention relates to an electronic volume control systemusable as to control the volume in audio instruments.

BACKGROUND ART

It is known that mechanisms for controlling the volume in audioinstruments are classified into analog type and electronic type.

The analog type volume controller controls the level of volume (which isreferred to "sound volume" herein) by using a variable resistor whichcan adjust the level of signal for regulating the sound volume.Normally, the variable resistor is adjusted by rotating a knob to anangular position corresponding to the desired sound volume.

On the other hand, a setting of sound volume has been digitized andstored in a memory. The sound volume can be adjusted when a preselecteddigital value is added to or subtracted from the stored value.

Such a type of electronic volume controllers are disclosed, for example,in Japanese Utility Model Laid-Open No. Sho 57-88316, Utility ModelLaid-Open No. Sho 59-140520, Utility Model Laid-Open No. Sho 61-158723,Patent Laid-Open No. Sho 61-242407, Patent Laid-Open No. Sho 62-21315,Patent Laid-Open No. Sho 64-10713, Patent Laid-Open No. Sho 64-36111,Patent Laid-Open No. Sho 64-81512, Utility Model Laid-Open No. Hei1-72718, Patent Laid-Open No. Hei 1-143511 and Patent Laid-Open No. Hei1-143512.

The electronic volume controller generally comprises an operation buttonfor increasing the sound volume (which will be referred to as "UP key")and another operation button for decreasing the sound volume (which willbe referred to as "DOWN key"). When the UP key or DOWN key is onceturned off immediately after it has been turn on (this operation will bereferred to as "single operation"), the preselected value is once addedto or subtracted from the setting value of sound volume stored in thememory. Thus, the sound volume will be increased or decreased by a givenamount of volume change. Such a volume control mode will be referred toas "single operation mode".

The electronic volume controllers frequently have such a function thatwhen the UP key or DOWN key is maintained at its ON state for a timeperiod exceeding a preselected time period (this operation will bereferred to as "continuous operation"), the preselected value is addedto or subtracted from the setting value of sound volume stored in thememory at each unit time so as to increase or decrease the sound volumeby an amount of volume change at each unit time until the UP key or DOWNkey is turned off. This volume control mode will be referred to as"continuous operation mode".

However, the conventional electronic volume controllers aredisadvantageous in that they are inferior in operability to the analogtype volume controller.

The analog type volume controller is very easy to be operated since adesired sound volume can be obtained merely by rotating a knob, asdescribed above. More particularly, an operator is only required torotate the knob rapidly to a position near a desired sound volume leveland then to rotate the knob gradually to a position accuratelycorresponding to the desired sound volume level.

The electronic volume controller uses the continuous operation mode whenit is desired to increase or decrease the sound volume rapidly to aposition near a desired sound volume. When such a position is reached,both the UP and DOWN keys are used to fine adjust the sound volume inthe single operation mode. In such a time, the sound volume will not beadjusted depending on the sense of the operator's finger(s), unlike theanalog type volume controller. Therefore, it cannot be avoided that theoperator feels cumbersome in handling the electronic volume controllerfor such a reason why the operator cannot sensuously detect the accuraterelationship between the key operation and the volume change in each ofthe single and continuous operation modes.

There is further known an electronic volume controller which can beadjusted by a rotatable knob. Since such a rotatable knob extendsoutwardly from the console panel of the controller, the knob frequentlyprovides any obstruction. It is thus desired that the electronic volumecontroller can have UP and DOWN keys capable of adjusting the soundvolume in conformity with the human's sense.

It is therefore an object of the present invention to provide anelectronic volume controller improved in operability.

DISCLOSURE OF INVENTION

To this end, the present invention provides an electronic volume controlsystem comprising a first operation button for varying the level ofvolume in the positive direction, a second operation button for varyingthe level of volume in the negative direction, and control means forincreasing or decreasing the level of volume by a given amount of volumechange in response to the operation of said first or second operationbutton, said control means being capable of being set at a fineadjustment mode in which the level of volume can be increased ordecreased by another amount of volume change less than said given amountof volume change, whereby said fine adjustment mode can be set if a timeinterval from a time point when one of said first and second operationbuttons is turned off to another time point when one of said first andsecond operation buttons is turned on is within a preselected timeperiod.

Said control means is preferably set at its fine adjustment mode onlywhen the operation button previously turned off is different from theoperation button subsequently turned on. This can be applied if thepreceding and subsequent operations are carried out by a singleoperation.

The control means is in one of two volume level adjustment modes, thatis, a single operation mode in which the volume of volume is varied by afirst amount of change each time when the first or second operationbutton is singly operated, and a single operation fine adjustment modein which the level of volume is varied by a second amount of volumechange less than said first amount of volume change each time when saidoperation button is singly operated and if a time interval from a timepoint when one of said first and second operation buttons is turned offto another time point when the other operation button changing the levelof volume in the direction opposite to that of said one operation buttonis turned on is within a first preset time period.

The control means preferably continues to perform the single operationfine adjustment mode so far as a time interval of operations of the sameoperation button through which its single operation is repeated aftersetting of said single operation fine adjustment mode is within a secondpreset time period. It is however preferred that if the time intervalexceeds said second preset time period, said single operation fineadjustment mode is released. If the second preset time period is equalto the first preset time period, the control means requires only onecounting means which can judge whether the time interval is within thefirst or second preset time period.

For the volume level adjustment, the control means can include, inaddition to the single operation mode, a continuous operation mode inwhich the level of volume is varied by a third amount of volume changefor each unit time during a continuous operation that the first orsecond operation button is maintained at its ON state for a third presettime period, and a continuous operation fine adjustment mode in whichthe level of volume is varied by a fourth amount of volume change lessthan the third amount of volume change for each unit time if a timeinterval from a time point when one of the first and second operationbuttons singly operated is turned off to another time point when theother operation button changing the level of volume in the directionopposite to that of said one operation button is turned on in acontinuous operation is within the first preset time period. Thiscontinuous operation fine adjustment mode can be applied to case wherethe operation button previously operated by a single operation is thesame as the operation button subsequently operated in the continuousoperation mode.

For the volume level adjustment, the control means may include, inaddition to the single and continuous operation modes, a singleoperation fine adjustment mode in which the volume level is varied by asixth amount of volume change less than the first amount of volumechange if a time interval from a time point when one of the first andsecond operation buttons in a continuous operation is turned off toanother time point when the other operation button changing the level ofvolume in the direction opposite to that of said one operation button isturned on by a single operation is within the first preset time period.This single operation fine adjustment mode can be also applied to casewhere the operation button previously operated by a continuous operationis the same as the operation button previously operated by a singleoperation. The single operation fine adjustment mode can be released, asdescribed.

For the volume level control, the control means may include, in additionto the continuous operation mode, a continuous operation fine adjustmentmode in which the level of volume is varied by an eighth amount ofvolume change less the third amount of volume change for each unit timeif a time interval from a time point when one of the first and secondoperation buttons operated by a continuous operation is turned off toanother time point when the other operation button changing the level ofvolume in the direction opposite to that of said one operation button isturned on by a continuous operation is within said first preset timeperiod. This continuous operation fine adjustment mode can be alsoapplied to case where the operation button previoualy operated by acontinuous operation is the same as the operation button subsequentlyoperated by a continuous operation.

Based on a time interval from the preceding button operation to thesubsequent button operation, the electronic volume control system of thepresent invention judges whether an operation button is subsequentlyoperated by an operator in connection with the preceding buttonoperation or independently or whether or not it is desired to regulatethe sound volume rapidly to near the desired level before a fineadjustment is carried out. Alternatively, the volume control systemjudges, in addition to the above judgment, whether or not the operationbutton previously operated is different from the operation buttonsubsequently operated and also whether the preceding and subsequentbutton operations are carried out by a continuous operation. In responseto these judgments, the volume control system sets the fine adjustmentmode such that the level of volume can be finely regulated with areduced amount of volume change.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a first embodiment of an electronic volumecontrol system constructed in accordance with the present invention.

FIG. 2 is a timing chart illustrating how the amount of volume change isdetermined in the electronic volume control system shown in FIG. 1.

FIG. 3 is a timing chart illustrating the single operation fineadjustment mode after a continuous operation in a second embodiment ofan electronic volume control system constructed in accordance with thepresent invention.

FIG. 4 is a timing chart illustrating how the amount of volume change isdetermined in a third embodiment of an electronic volume control systemconstructed in accordance with the present invention.

FIGS. 5 to 7 are flowcharts illustrating a fourth embodiment of anelectronic volume control system constructed in accordance with thepresent invention.

FIG. 8 is a block diagram of the fourth embodiment of an electronicvolume control system constructed in accordance with the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in connection with a modewhere an electronic volume control system constructed in accordance withthe present invention is applied as a sound volume control means in anaudio system.

First Embodiment

Referring to FIG. 1, the electronic volume control system of the presentinvention comprises an UP key 1 and a DOWN key 2. When one of these UPand DOWN keys 1 or 2 is operated, a processing circuit 7 in a controlcircuit 3 determines a value to be added to or subtracted from volumesignals, based on a value inputted from a timer 9. The timer 9 counts atime interval from a time point when one of the keys 1 or 2 is turnedoff to another time point when one of the keys 1 or 2 is turned on andoutputs it. The timer 9 also performs a counting for judging whether thekey is operated in the single or continuous operation mode. Theprocessing circuit 7 reads out the present level of volume and theamount of volume change corresponding to the succeedingly selected modefrom a memory 8, on which the level of volume is calculated. Theprocessing circuit 7 further causes the memory 8 to store the calculatedvolume level and at the same time outputs it to an electronic volume IC4. The electronic volume IC 4 is in response to the received volumelevel to determine the sound volume to be outputted by a speaker 6,based on which sound volume the input audio signals are transformed. Itis now assumed that in this embodiment, the sound volume is increased ordecreased by one step (e.g. 2 dB) as the amount of volume change in thevolume signal is increased or decreased by "1". The input audio signalstransformed by the electronic volume IC 4 are amplified by a poweramplifier 5, the amplified signals being then fed to the speaker 6whereat these signals are converted into voice.

The relationship between the operation of the UP and DOWN keys 1, 2 andthe sound volume will be described below.

In this embodiment, it is assumed that the value of addition orsubtraction induced in the control circuit 3 from the operation of theUP or DOWN key 1 or 2 is as follows:

(1) Four steps/one operation in the single operation mode;

(2) One step/one operation in the single operation fine adjustment mode;and

(3) Two steps/200 msec. in the continuous operation mode.

The "single operation mode" is one that the key operation is singlyperformed during the third preset time period (e.g. 200 msec.) after oneof the UP key 1 or DOWN key 2 has been turned on and also that isselected at any mode other than the "single operation fine adjustmentmode".

The "continuous operation mode" is selected when the operation key ismaintained at its ON state for a time period exceeding the third presettime period.

The "single operation fine adjustment mode" is automatically selectedwhen a time interval t from the precedent OFF operation to the presentON operation is less than the first preset time period Δt (e.g. twoseconds in this embodiment) and if the previously operated key isdifferent from the key succeedingly operated by the single operation,irrespectively of whether the precedent key operation is the single orcontinuous operation mode. The single operation fine adjustment mode iscontinued when a time interval from one key operation to another keyoperation in the same key repeatedly operated in the single operationmode is within the second preset time period (e.g. two seconds in thisembodiment). If the time interval exceeds the second preset time period,the single operation fine adjustment mode is released.

FIG. 2 shows a timing chart illustrating a volume control carried outaccording to the respective modes.

(a) This stage represents when the UP key 1 is initially operated by asingle operation after the electronic volume control system has beenstarted. In this case, the single operation mode is selected to increasethe sound volume at the rate of four steps/one operation.

(b) This stage is obtained when the DOWN key 2 is turned on by a singleoperation within a time period less than two seconds from the OFFoperation of the stage (a). In this case, the single operation fineadjustment mode is selected to decrease the sound volume at the rate ofone step/one operation.

(c) This stage is accomplished when the UP key 2 is operated by a singleoperation within a time period less than two seconds from the OFFoperation of the stage (b). The single operation fine adjustment mode isselected to increase the sound volume at the rate of one step/oneoperation.

As shown in the stages (b) and (c), the single operation fine adjustmentmode is selected when one of the operation keys different from theprevious operation key is operated by a single operation before twoseconds elapses from the preceding OFF operation.

(d) This stage is one that the DOWN key 2 is operated by a singleoperation after two seconds have elapsed from the OFF operation in thestage (c). The single operation mode is selected to decrease the soundvolume at the rate of four steps/one operation since two seconds haselapsed from the preceding OFF operation.

(e) This stage is one that the DOWN key 2 is operated in a continuousoperation mode.

As the DOWN key 2 is turned on, the control circuit 3 of this embodimentcannot promptly judge whether the DOWN key 2 is operated by a single ora continuous operation. In such a case, this embodiment is so adaptedthat the first change of sound volume follows the single operation modesince the previously operated key is the same as the subsequentlyoperated key and that the key operation is shifted to the continuousoperation mode if the key is maintained at its ON state after passage ofthe third preset time period from the key operation (which is 200 msec.in this embodiment). In the stage (e), thus, the sound volume will befirst decreased by four steps and then by two steps/200 msec. Since thesame key is succeedingly operated in this case, the sound volume iscontrolled in the above mode, irrespectively of whether or not the timeinterval is less than two seconds.

(f) This stage shows the DOWN key 2 operated by a single operation.Since the previously operated key is the same as the succeedinglyoperated key in this stage (f), the single operation mode will beselected to reduce the sound volume at the rate of four steps/oneoperation, irrespectively of whether or not a time interval from the keyoperation of the stage (e) is less than two seconds.

(g) This stage represents that the UP key 1 is operated by a continuousoperation. For the same reason as in the stage (e), the sound volume isfirst increased by four steps and thereafter by two steps/200 msec.

(h) In this stage, the DOWN key 2 is operated by a single operationafter two seconds have elapsed from the key-off operation in the stage(g). The single operation mode is selected to decrease the sound volumeat the rate of four steps/one operation.

(i) This stage represents that the UP key 1 is operated by a continuousoperation in less than two seconds from the OFF operation of the stage(h). For the same reason as in the stage (e), the sound volume is firstincreased by one step (in accordance with the fine adjustment mode sincethe previously and succeedingly operated keys are different from eachother). Thereafter, the sound volume is increased at the rate of twosteps/200 msec..

(j) In this stage, the DOWN key 2 is operated by a single operation; atime interval from the key-off operation in the stage (i) is less thantwo seconds; and the previously and succeedingly operated keys aredifferent from each other. The fine adjustment mode is thus selected todecrease the sound volume at the rate of one step/one operation.

(k) The UP key 1 is operated in the continuous operation mode. From thefact that the previously operated key is the same as the succeedinglyoperated key, the sound volume is first increased by four steps and thenat the rate of 2 steps/200 msec..

(l) This stage shows that the DOWN key 2 is operated by a continuousoperation. For the same reason as in the stage (e), the sound volume isfirst decreased by one step (in accordance with the fine adjustmentmode) and then at the rate of two steps/200 msec..

(m) This stage shows that the UP key 1 is operated by a continuousoperation. For the same reason as in the stage (e), the sound volume isfirst increased by four steps and then at the rate of two steps/200msec..

In stages other than the above stages, the level of sound volume will becontrolled in accordance with the volume level control modes (1), (2)and (3) aforementioned.

In such a manner, this embodiment is adapted to determine the amount ofsound volume change on selection of the single operation mode, dependingon the time interval from the preceding key-off operation to the presentkey-on operation and whether or not the previously operated key is thesame as the succeedingly operated key. Therefore, the operator can moreeasily control the sound volume into the desired level.

Although this embodiment has been described as to the electronic volumecontroller including the single and continuous operation modes forcontrolling the sound volume, the present invention may be similarlyapplied to an electronic volume controller having only a singleoperation mode with fine adjustment.

Second Embodiment

The second embodiment of an electronic volume controller constructed inaccordance with the present invention will be described below.

When a time interval t from the preceding key-off operation to thepresent key-on operation is less than the first preset time period Δt(e.g. two seconds) and if the preceding key operation is in thecontinuous operation mode and a present key operation is in the singleoperation mode, the second embodiment is automatically adapted to selectthe fine adjustment mode even if the previously operated key is the sameas the succeedingly operated key. This is different from the electronicvolume controller of the first embodiment.

FIG. 3(A) shows a modification of the operation corresponding to thestage (f) of FIG. 2. When in the stage (e), the DOWN key 2 is operatedby a single operation in less than two seconds after the same DOWN key 2in a continuous operation has been turned off, the control circuit 3selects the fine adjustment mode to decrease the sound volume at therate of one step/one operation.

FIG. 3(B) shows that the sound volume is increased in the fineadjustment mode after it has been increased in the continuous operationmode, in contrast with that of FIG. 3(A). Similarly, the control circuit3 selects the fine adjustment mode to increase the sound volume at therate of one step/one operation when the UP key 1 is operated by a singleoperation in less than two seconds after the same UP key 1 has beenturned off.

Since the fine adjustment mode is selected even if a key is previouslyoperated in the continuous operation mode and also the same key islately operated and when the time interval between these two keyoperations is less than two seconds, the sound volume can be more easilyadjusted.

Although this embodiment is such that the amount of sound volume changewhen the different key from the previously operated key is operated toselect the fine adjustment mode is the same as that when the same key asthe previously operated key is operated to select the fine adjustmentmode, the amounts of sound volume change different from each other maybe used.

Third Embodiment

The third embodiment of an electronic volume controller constructed inaccordance with the present invention will be described below.

The third embodiment is set such that the fine adjustment mode isselected when the time interval t from the preceding key operation tothe subsequent key operation is less than a preset time period Δt (e.g.two seconds) and even if the continuous operation mode was selected.

Further, the third embodiment will not judge whether or not thepreviously operated key is the same as the succeedingly operated key.

In this embodiment, values to be added or subtracted at the controlcircuit 3 when the continuous operation mode is selected are as follows:

(1) Four steps/200 msec. in the continuous operation mode; and

(2) Two steps/200 msec. in the contiuous operation fine adjustment mode.

Values to be added or subtracted at the control circuit 3 when thesingle operation mode is selected are the same as those of the firstembodiment.

FIG. 4(A) shows a modification of the operation corresponding to thestage (e) of FIG. 2. After the UP key 1 or DOWN key 2 has been operatedand when the UP key 1 or DOWN key 2 is again turned on in less than twoseconds to select the continuous operation mode, the control circuit 3selects the fine adjustment mode to vary the sound volume at the rate oftwo steps/200 msec., rather than the rate of four steps/200 msec.

On the other hand, when the UP key 1 or DOWN key 2 is turned on toselect the continuous operation mode after passage of a time periodexceeding two seconds from the key-off operation of the UP key 1 or DOWNkey 2, the control circuit 3 varies the sound volume at the rate of foursteps/200 msec., as shown in FIG. 4(B).

If the values to be added or subtracted in the continuous operation modebecome different depending on the time interval between the precedingand subsequent key operations, the operator can more easily control thesound volume into the desired level.

Although it has been described that this embodiment does not judgewhether or not the previously operated key is the same as thesubsequently operated key, it may be modified such that the fineadjustment mode is selected only when the key different from thepreviously operated key is operated.

Moreover, the amount of sound volume change when the different key isoperated to select the fine adjustment mode may be different from thatwhen the same key is operated to select the fine adjustment mode.

Fourth Embodiment

FIG. 8 shows the fourth embodiment of an electronic volume controllerconstructed in accordance with the present invention. In addition of thearrangement shown in FIG. 1, the processing circuit 7 of the fourthembodiment is connected to UP-key and DOWN-key counters 10, 11. Further,the memory 8 includes a first flag area 8a and a fine-adjustment flagarea 8b.

In this embodiment, values to be added or subtracted at the controlcircuit 3 in response to the operation of the UP key 1 or DOWN key 2 areas follows:

(1) Four steps/one operation in the single operation mode;

(2) One step/one operation in the single operation fine adjustment mode;

(3) Four steps/200 msec. in the continuous operation mode; and

(4) Two steps/200 msec. in the continuous operation fine adjustmentmode.

The single operation fine adjustment mode is selected if the singleoperation has been previously carried out and when the single key-onoperation changing the level of volume in the direction opposite to thatof the preceding key operation is performed in less than the firstpreset time period (e.g. two seconds). Furthermore, the single operationfine adjustment mode is selected if the continuous operation mode hasbeen previously carried out and when the single key-on operation is madein less than two seconds, irrespectively of whether or not the directionof changing the level of volume is the same as that of the preceding keyoperation. After selected, the single operation fine adjustment modecontinues so far as the time interval when the same key is repeatedlyturned on and off is in less than the second preset time period (thesame as the first preset time period, that is, two seconds in thisembodiment).

The continuous operation fine adjustment mode is selected when thecontinuous key-on operation is within the time interval less than twoseconds, irrespectively of whether the preceding key operation is in thesingle or continuous operation mode and also irrespectively of whetheror not the direction of changing the level of volume is the same as thatof the preceding key operation.

The first and second preset time period equal to two seconds are countedby the UP-key counter 10 and DOWN-key counter 11, respectively. Moreparticularly, a value representing two seconds has been set in one orboth of the counters 10 and 11 at a certain timing. Such a value will becounted down. After passage of two seconds, the outputs of the counters10 and 11 become "0". If so done, it is judged that the time intervalpassed through two seconds.

The operation of this electronic volume controller will be describedwith reference to flowcharts shown in FIGS. 5 to 7.

First of all, the control circuit 3 judges whether or not any key isturned on (step 100). In the key-off state, the control circuit 3renders the first flag in the memory area 8a "0" (step 101). In thekey-on state, the control circuit 3 then judges whether or not the firstflag in the memory area 8a is "1" (step 102). The first flag is made "1"in transition to the continuous operation mode and maintained "1" so faras the continuous operation mode continues. As the continuous operationmode is terminated, the first flag becomes "0". If the first flag is"1", the process goes to step 121 bypassing the subsequent steps103-120.

If the judgment is "NO" at the step 102, the control circuit 3 causesthe timer 9 to set the third preset time period equal to 500 msec. (step103). The control circuit 3 then judges whether or not the third presettime period, 500 msec., is counted up before any key-off operation (step104). If the judgment is "NO" at the step 104, the control circuit 3judges that the key operation is a single operation and the process goesto step 105. If the judgment is "YES" at the step 104, the controlcircuit 3 judges that the key operation is a continuous operation andthe process goes to step 116.

Operation after it has been judged at the step 104 that the keyoperation is the single operation will be described with reference tothe flowchart of FIG. 6.

The control circuit 3 first judges whether or not an operation key isthe UP key 1 (step 105). If the operated key is the UP key 1, it is thenjudged whether or not the output of the DOWN-key counter 11 is "0" (step106). If the judgement is "YES" at the step 106, it means that (1) theUP key 1 has been previously operated in the single operation mode; (2)the time interval from the preceding key-off operation of the DOWN key 2has exceeded two seconds or (3) the UP key 1 has been previouslyoperated in the single operation fine adjustment mode with the timeinterval from the key-off operation exceeded two seconds, which will bedescribed in more detail later. In such a case, the UP rate in thesingle operation mode will be set at step 107. If the judgment is "NO"at the step 106, it means that (1) the time interval from the precedingkey-off operation of the DOWN key 2 is less than two seconds or (2) theUP key 1 is previously operated in the single operation fine adjustmentmode, with the time interval from the preceding key-off operation of theDOWN key 2 being less than two seconds. In such a case, it is judgedthat the operation mode is the single operation fine adjustment mode.The UP rate in that fine adjustment mode is set at step 108. In thesingle operation fine adjustment mode, a value of two seconds is set inthe DOWN-key counter 11 at the succeeding step 109. Furthermore, a valueof two seconds is also set in the UP-key counter 10 at step 110,irrespectively of whether the controller is in the single operation modeor single operation fine adjustment mode.

If the judgement is "NO" at the step 105, that is, the DOWN key 2 hasbeen operated, the same process as carried out through the steps 106 to110 is carried out through steps 111 to 115.

Thereafter, the process goes to step 129 whereat the level of volume ischanged in accordance with an UP or DOWN rate determined at the step107, 108, 112 or 113. The process then returns to its start pointthrough a loop 103. In the loop 103, for example, counting-downoperations are carried out in the UP-key and DOWN-key counters 10, 11for each unit time.

When the UP key 1 has been previously operated by the single operationand the DOWN key 2 is now operated by the single operation and if thetime interval from when the UP-key counter 11 is set with two seconds atthe step 110 to when the DOWN key 2 is turned on is in less than twoseconds, the judgement at step 111 is "NO". Thus, the single operationfine adjustment mode will be set at step 113. On the other hand, if theUP key 1 is successively operated twice by the single operation, theDOWN-key counter 11 will not be set with two seconds unless theproceding key operation is in the single operation fine adjustment mode.Therefore, the judgement at the step 106 is "YES". The single operationmode will be continued. In other words, the process will go to thesingle operation fine adjustment mode only when the succeeding singleoperation is in the direction opposite to the preceding single operationand the time interval is less than two seconds. This is true of when theDOWN key 2 has been operated by the preceding single operation.

The continuous operation mode and continuous operation fine adjustmentmode will be described with reference to the flowcharts shown in FIGS. 5and 7.

If the judgment at the step 104 is "YES", it is judged that the keyoperation is the continuous operation. The first flag in the memory area8a is set at "1" (step 116). It is then judged at steps 117 and 118whether or not this continuous operation is carried out in less than thetime interval, that is, two seconds. At the step 117, it is judgedwhether or not the output of the UP-key counter 10 is "0". At the step118, it is judged whether or not the output of the DOWN-key counter 11is "0". If "NO" in either of the step 117 or 118, the fine adjustmentmode flag is set to "1" at step 120. In other words, this operationenables the continuous operation fine adjustment mode to be set. On theother hand, the fine adjustment mode flag can be set to "0" at step 119only when both the judgments at the steps 117 and 118 are "YES". Namely,the continuous operation mode can be set.

If the fine adjustment mode flag is set to "0" or "1" at the step 119 or120 or when it is judged at the step 102 that the first flag is "1", itis judged whether or not the operated key is the UP key 1 (step 121). Ifit is the UP key 1, it is then judged whether or not the fine adjustmentmode flag is "1" (step 122). UP rates for the continuous operation fineadjustment mode and continuous operation mode will be set at steps 124and 123, respectively. Even if the operated key is the DOWN key 2, thesame process is carried out through steps 125 to 127. Thereafter, theUP-key and DOWN-key counters 10 and 11 are set to two seconds (step128). In the subsequent step 129, the level of volume is changed inaccordance with UP or DOWN rate which has been set at the step 123, 124,126 or 127. Thereafter, the process similarly returns to its start pointvia the loop 130.

So far as the key-on operation is continued in the continuous operationmode or continuous operation fine adjustment mode, the judgments at thesteps 100 and 102 become "YES". Thereafter, the loop control returningto the step 100 through the steps 121 to 130 is continuousky carriedout. One the key-off operation, the judgment at the step 100 is "NO".Thus, the first flag is set to "0" at the step 101.

A concrete example of volume level control mode when various types ofkeys are operated after, for example, the UP key 1 has been turned offby the continuous operation, will be described below.

If the DOWN key 2 is operated by the single operation in less than twoseconds after the UP key 1 has been operated by the continuousoperation, the process goes to step 111 through steps 100-105. At thestep 111, the judgment becomes "NO". The system is set to the singleoperation fine adjustment mode at step 113. If the UP-key 1 is operatedby the single operation less than two seconds after the UP-key 1 hasbeen operated by the continuous operation, the judgment at the step 106becomes "NO". The system is set to the single operation fine controlmode at step 108. More particularly, the system will be set to thesingle operation fine adjustment mode if the single operation is carriedout in less than two seconds after the continuous key-off operation,irrespectively of the type of key.

Similarly, after, for example, the UP key 1 has been turned off by thecontinuous operation and when the continuous operation is againselected, the system is set to the continuous operation fine adjustmentmode if the time interval is less than two seconds, irrespectively ofthe type of key. This is because if the judgment is "NO" in either ofthe step 117 or 118, the fine adjustment mode flag is set to "1" to setthe continuous operation fine adjustment mode.

In order to secure these operations, a value of two seconds is set tothe UP-key and DOWN-key counters 10, 11 at step 128 in the precedingcontinuous operation.

In this embodiment, further, the single operation fine adjustment modeis continued only when the time interval when the same key is repeatedlyturned on and off is in less than the second preset time period equal totwo seconds after the single operation fine adjustment mode has beenset. After the single operation fine adjustment mode for the UP key 1has been set at the steps 105, 107 or 108 and when a value of twoseconds is set to the DOWN-key counter 11 at the step 109 and the UP key1 is subsequently operated in less than two seconds, the singleoperation fine adjustment mode can be again continued at the steps 105,107 and 108. The step 114 is also required to continue the singleoperation fine adjustment mode by the DOWN key 2.

If both the first and second preset time periods are set to two secondsas in this embodiment, the counting can be performed by the UP-key andDOWN-key counters 10, 11. This is advantageous in that two types ofcounting operations can be accomplished without any additional counter.

It is to be understood that the present invention is not limited to theaforementioned embodiments. The present invention may be similarlyapplied to any combination of the aforementioned embodiments.Furthermore, the electronic volume controller of the present inventioncan be set at the single operation fine adjustment mode when the timeinterval is less than the first preset time period set to be relativelyshort, even if two successive single key operation are carried out tochange the level of volume in the same direction.

ADVANTAGE OF THE INVENTION

As will be apparent from the foregoing, the present invention can beimprove the electronic volume controller in operability since the amountof volume level change in the electronic volume controller can be finelyregulated in the opposite or the same directions after the sound volumeis rapidly adjusted to a level near the desired volume level.

I claim:
 1. An electronic volume control system comprising:a firstoperation button for varying the level of volume in the positivedirection; a second operation button for varying the level of volume inthe negative direction; and control means for increasing or decreasingthe level of volume by a given amount of volume change in response tothe operation of one of said first and second operation buttons, saidcontrol means having a fine adjustment mode in which the level of volumecan be increased or decreased by another amount of volume change lessthan said given amount of volume change, said control system beingplaced into said fine adjustment mode when a time interval, from a timepoint wherein one of said first and second operation buttons is turnedoff to another time point wherein one of said first and second operationbuttons is turned on, is within a preset time period.
 2. The electronicvolume control system of claim 1, wherein said control means is placedinto said fine adjustment mode only when the operation button previouslyturned off differs from the operation button subsequently turned on. 3.The electronic volume control system of claim 1, wherein said controlmeans has a single operation gross adjustment mode in which the level ofvolume is varied by a first amount of volume change during a singleoperation of one of said first and second operation buttons, and asingle operation fine adjustment mode in which the level of volume isvaried by a second amount of volume change less than said first amountof volume change during said single operation of one of said first andsecond operation buttons, the control means operating in said singleoperation fine adjustment mode when said one of said first and secondoperation buttons is singly operated and when a time interval from afirst time point wherein one of said first and second operation buttonsis turned off by a single operation to a second time point wherein oneof said first and second operation buttons is turned on by a singleoperation, is within a first preset time period.
 4. The electronicvolume control system of claim 3, wherein said control means remains inthe single operation fine adjustment mode when a time interval betweenoperations of the same operation button corresponding to said singleoperation fine adjustment mode is within a second preset time period andwherein if the time interval exceeds said second preset time period,said single operation fine adjustment mode is released.
 5. Theelectronic volume control system of claim 4, wherein said second presettime period is equal to said first preset time period.
 6. The electronicvolume control system of claim 1, wherein said control means includes:asingle operation gross adjustment mode in which the level of volume isvaried by a first amount of volume change during a single operation ofone of said first and second operation buttons; a continuous operationgross adjustment mode in which the level of volume is varied by a secondamount of volume change for each unit time during a continuous operationof one of said first and second operation buttons, when said one of saidfirst and second operation buttons is maintained at its ON state for afirst preset time period, and a first continuous operation fineadjustment mode in which the level of volume is varied by a third amountof volume change less than the second amount of volume change for eachunit time when a time interval, from a first time point wherein one ofthe first and second operation buttons is turned off by a singleoperation to a second time point, wherein the other operation button isturned on and continuously operated, is within a second preset timeperiod.
 7. The electronic volume control system of claim 6, wherein saidcontrol means further has a second continuous operation fine adjustmentmode in which the level of volume is varied by a fourth amount of volumechange less than the second amount of volume change for each unit timewhen a time interval, from said first time point to a third time point,wherein the same operation button as in the previous button operation isturned on and continuously operated, is within a third preset timeperiod.
 8. The electronic volume control system of claim 1, wherein saidcontrol means includes:a single operation gross adjustment mode in whichthe level of volume is varied by a first amount of volume change eachtime during a single operation of one of said first and second operationbuttons; a continuous operation gross adjustment mode in which the levelof volume is varied by a second amount of volume change for each unittime during a continuous operation of one of said first and secondoperation buttons, when said one of said first and second operationbuttons is maintained at its ON state for a first preset time period;and a first single operation fine adjustment mode in which the volumelevel is varied by a third amount of volume change less than the firstamount of volume change when a time interval, from a first time point,wherein said one of the first and second operation buttons beingcontinuously operated is released, to a second time point, wherein theother operation button is turned on by a single operation is within asecond preset time period.
 9. The electronic volume control system ofclaim 8, wherein said control means further includes:a second singleoperation fine adjustment mode in which the level of volume is varied bya fourth amount of volume change less than the second amount of volumechange for each unit time when a time interval from said first timepoint to a third time point, wherein the same operation button as in theprevious button operation is turned on by a single operation, is withina third preset time period.
 10. The electronic volume control system ofclaim 8, wherein said control means remains in the single operation fineadjustment mode when a time interval between operations of the sameoperation button, corresponding to said single operation of said one ofsaid first and second operating buttons is within a third preset timeperiod and when the time interval exceeds said third preset time period,said single operation fine adjustment mode is released.
 11. Theelectronic volume control system of claim 10, wherein said third presettime period is equal to said second preset time period.
 12. Theelectronic volume control system of claim 1, wherein said control meansincludes:a continuous operation gross adjustment mode in which the levelof volume is varied by a first amount of volume change for each unittime during a continuous operation of one of said first and secondoperation buttons, when said one of said first and second operationbuttons is maintained at its ON state for a first preset time period,and a first continuous operation fine adjustment mode in which the levelof volume is varied by a second amount of volume change less than thefirst amount of volume change for each unit time when a time intervalfrom a first time point, wherein said one of the first and secondoperation buttons in said continuous operation is turned off, to asecond time point, wherein the other operation button is turned on bysaid continuous operation, is within a second preset time period. 13.The electronic volume control system of claim 12, wherein said controlmeans further includes:a continuous operation fine adjustment mode inwhich the level of volume is varied by a third amount of volume changeless than the first amount of volume change for each unit time when atime interval, from said first time point to a third time point, whereinthe same operation button as in the previous button operation is turnedon by said continuous operation, is within a third preset time period.